fix(home): 首切频道预取并保留播放画面

lib/core/data/services/home_feed_controller.dart

@@ -52,6 +52,14 @@ class HomeFeedController extends ChangeNotifier {
     _notifyIfCurrent(HomeFeedChannel.recommend);
   }
 
+  /// 后台预取漫剧与真人剧首屏，不切换频道，也不影响当前列表。
+  Future<void> prefetchChannels() async {
+    await Future.wait([
+      _prefetchChannel(HomeFeedChannel.anime),
+      _prefetchChannel(HomeFeedChannel.live),
+    ]);
+  }
+
   /// 同步切到目标频道；有缓存先渲染，无缓存时复用或等待在飞请求。
   Future<void> selectChannel(HomeFeedChannel next) async {
     if (next == _channel) return;
@@ -59,7 +67,9 @@ class HomeFeedController extends ChangeNotifier {
     _notify();
     final state = _state(next);
     if (state.dramas.isNotEmpty) {
-      if (!state.loading) {
+      if (state.skipNextRefresh) {
+        state.skipNextRefresh = false;
+      } else if (!state.loading) {
         unawaited(_refresh(next, keepData: true));
       }
       return;
@@ -67,6 +77,7 @@ class HomeFeedController extends ChangeNotifier {
     if (state.loading) {
       final inFlight = state.inFlight;
       if (inFlight != null) await inFlight;
+      state.skipNextRefresh = false;
       return;
     }
     await _refresh(next, keepData: false);
@@ -126,6 +137,13 @@ class HomeFeedController extends ChangeNotifier {
     return operation;
   }
 
+  Future<void> _prefetchChannel(HomeFeedChannel channel) async {
+    final state = _state(channel);
+    if (state.loaded || state.loading) return;
+    final success = await _refresh(channel, keepData: false);
+    if (success && !_disposed) state.skipNextRefresh = true;
+  }
+
   Future<bool> _performRefresh(
     HomeFeedChannel channel, {
     required bool keepData,
@@ -200,4 +218,5 @@ class _ChannelFeedState {
   String? lastError;
   int requestSeq = 0;
   Future<bool>? inFlight;
+  bool skipNextRefresh = false;
 }